I found thin black Delrin sheets available from McMaster-Carr and onlinemetals.com. Has anyone ever tried using this for dark slides? It's lighter than aluminum, on the order of Garolite XX, and has nice low-friction properties. I may just order a 1/32" sheet to play around with, but it would be nice to know ahead of time if there are any issues with this material. BTW, I purchased a thin (0.023") sheet of carbon-fiber material recently. It won't do for a dark slide, at least this thin - it's not entirely opaque! Open areas in the weave lead to optical pinholes. A thicker sheet might not suffer from this, but aluminum, garolite, and (I hope) Delrin don't have this problem and are less costly as well.